I'm against Turkiye returning the F-35 project except for industrial participation. Greek F-35 is not an immediate threat. Even if the US offers delivery slots reserved for the USAF Greece won't get any F-35 before the end of 2028 and most likely get their first F-35s in 2031 like the Czech Republic. If relations with the US improve Navy should get 20 F-35Bs and that is it.
So how should Turkiye counter F-35s other than deploying the 5th-generation air superiority fighter Kaan?
We should deploy a network of passive radars, L band, and UHF/VHF band early warning radars.
We should deploy satellites and pseudo satellites (both EO and SAR) to watch the air bases of Greece. We should also listen to those bases if you can't listen to the bird, listen to the base.
Invest in both land-based and airborne EW assets like (Koral-II, IHA-SOJ, and Hava-SOJ)
The carrying capacity of F-35s in stealth configuration is limited, we should defend critical infrastructure against effectors launched/dropped by F-35s so we should invest in short-range/point air defense to hit whatever F-35s launch/drop. Hit the payload, if you can't hit the bird.
We should mass produce long-range precision weapons in sufficient numbers that can cover every inch of Greece. We should also create a new missile forces command. New missile command should have cruise missiles(300+km), ballistic missiles(300+km), and kamikaze UAVs(300+km) and should be responsible for conducting strategic strikes to degrade enemy airforce operation capability. The command should prioritize aircraft hangars, control towers, fuel production and refueling facilities, maintenance, rearm and repair facilities, command centers, and armories. Hit the base, infrastructure, and logistic chain if you can't hit the bird.
Produce precision long-range artillery rounds. 70+km is easily achievable with current 155mm/52cal artillery guns. Produce huge amounts of rocket artillery up to 300km range. This will have a strategic effect at a tactical level.
Quickly complete long-range Anka-III deep strike UAV project and station it deep inside Anatolia to have second strike capability in case of an unprovoked attack by the enemy.
Quickly complete Gezgin and Sub-Atmaca so that our submarines can hit targets deep inside enemy territory.
Increase production capacity for ammunition, missiles, and kamikaze UAVs for a long confrontation and remind the other side and relevant parties that we have what it takes to continue the war and that war won't be over in a week.
F-35 is a strong asset but it is not a silver bullet to win a war.